UMIVEBSITY  OF   CALIFORNIA  PPBLICATIOH8 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 


BERKELEY,  CALIFORNIA 


VINEGAR  FROM  WASTE  FRUITS 


BY 

W.  V.  CRUESS 


BULLETIN  No.  287 

October,  1917 


UNIVERSITY  OF  CALIFORNIA  PRESS 

BERKELEY 

1817 


Benjamin  Ide  Wheeler,  President  of  the  University. 

EXPEEIMENT  STATION  STAFF 

HEADS  op  divisions 

Thomas  Forsyth  Hunt,  Director. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;  Plant  Breeding. 

Hubert  E.  Van  Norman,  Vice-Director;  Dairy  Management. 

William  A.  Setchell,  Botany. 

Myer  E.  Jaffa,  Nutrition. 
*Bobert  H.  Loughridge,  Soil  Chemistry  and  Physics   (Emeritus). 

Charles  W.  Woodworth,  Entomology. 

Ealph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural  Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 

Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

James  T.  Barrett,  Plant  Pathology. 

Fritz  W.  Woll,  Animal  Nutrition. 

Walter  Mulford,  Forestry. 

W.  P.  Kelley,  Agricultural  Chemistry. 

H.  J.  Quayle,  Entomology. 

D.  T.  Mason,  Forestry. 

J.  B.  Davidson,  Agricultural  Engineering. 

Elwood  Mead,  Bural  Institutions. 

H.  S.  Reed,  Plant  Physiology. 

W.  L.  Howard,  Pomology. 
IFrank  Adams,  Irrigation  Practice. 

C.  L.  Roadhouse,  Dairy  Industry. 

William  G.  Hummel,  Agricultural  Education. 

John  E.  Dougherty,  Poultry  Husbandry. 

S.  S.  Rogers,  Olericulture. 

David  N.  Morgan,  Assistant  to  the  Director. 

Mrs.  D.  L.  Bunnell,  Librarian. 

Division  of  Viticulture 
F.  T.  Bioletti  W.  V.  Cruess 

J.  R.  Zion 


*  Died  July  1,  1917. 

f  In  co-operation  with  office  of  Public  Roads   and  Rural   Engineering,   U.   S. 
Department  of  Agriculture. 


VINEGAR  FROM  WASTE  FRUITS* 

By  W.  V.  CRUESS 


Fruit,  unsuitable  for  sale  fresh,  for  drying  or  for  canning,  may 
often  be  used  for  vinegar  making  or  for  the  manufacture  of  acetic- 
acid  from  which  to  produce  acetone,  used  in  the  manufacture  of  high 
explosives.  A  ton  of  apples,  grapes,  or  most  deciduous  fruits,  will 
yield  from  MO  to  175  gallons  of  juice  suitable  for  vinegar  making. 
Oranges  will  yield  about  100  to  125  gallons.  Apples  will  yield  about 
75  pounds  of  acetic  acid  per  ton,  grapes  about  150  pounds,  and 
oranges  about  50  pounds.  At  15  cents  per  gallon,  the  vinegar  from 
a  ton  of  apples  or  grapes  is  worth  approximately  $23,  and  from  a 
ton  of  oranges  $15.  Grapes  contain  nearly  twice  as  much  sugar  as 
apples,  and  the  vinegar  is  correspondingly  stronger.  The  figures 
given  are  based  on  the  assumption  that  the  grapes  are  not  diluted 
with  water.  At  $2  per  gallon  for  acetone,  the  acetone  from  a  ton  of 
apples  is  worth  about  $7,  of  grapes  about  $13,  and  of  oranges 
about  $4.50. 

There  is  usually  a  local  demand  for  vinegar  and  those  having 
surplus  fruit  can  make  vinegar  for  their  own  and  for  their  neighbors' 
use.  It  is  often  possible  to  build  up  a  profitable  local  trade  and  then 
gradually  increase  the  output,  so  that  a  business  of  considerable  size 
can  finally  be  established.  Profits  in  vinegar  making  are  moderate 
and  the  prospective  manufacturer  should  realize  this  fact  before 
undertaking  it  on  a  large  scale.  Acetone  for  explosives  is  also  in 
demand,  but  its  manufacture  involves  the  installation  of  extensive 
equipment  and  it  should,  therefore,  be  undertaken  only  on  a  large 
scale  and  in  a  locality  within  easy  reach  of  a  large  supply  of  cheap 
fruit.  The  Fresno  and  other  vineyard  districts  have  large  amounts 
of  cull  and  second-crop  grapes  and  raisin  seeds  suitable  for  acetone 
production,  while  citrus  districts  like  Redlands  or  Riverside  have  a 
large  supply  of  cull  oranges  not  utilized  at  present,  but  which  are 
suitable  for  this  purpose. 

It  is  proposed  here  to  discuss  briefly  the  principles  of  vinegar 
manufacture  rather  than  to  describe  large-scale  equipment.  If  the 
principles  are  thoroughly  understood,  methods  of  applying  them  to 
large  or  small-scale  manufacture  can  be  devised.  Acetone  is  pro- 
duced by  the  destructive  distillation  of  calcium  or  sodium  acetate 

*  Supplementary  to  " Grape  Vinegar"   (Bull.  227,  by  F.  T.  Bioletti). 


170 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


formed  from  acetic  acid  obtained  by  the  distillation  of  vinegar. 
Vinegar  making  is,  however,  one  of  the  principal  steps  in  the  process 
and  should  be  well  understood. 


Fig.  1. — Waste  apples,  peels,  and  cores  used  in  vinegar  making. 


Raw  Materials. — Vinegar  for  table  use  requires  fairly  sound  and 
clean  fruit.  For  acetone  manufacture,  the  condition  of  the  fruit  is 
not  important.  Any  of  the  common  California  fruits,  except  lemons, 
can  be  used  and  also  inferior  dried  fruits.  Cannery  waste,  such  as 
peels  and  cores,  will  make  a  satisfactory  vinegar  if  clean ;  otherwise 
it  may  be  used  for  acetic  acid  or  acetone. 

Crushing. — Crushers  suitable  for  grapes  and  all  varieties  of  fruits 
without  stones  are  available  in  sizes  varying  from  those  suitable  to 
a  small  kitchen  to  those  having  a  capacity  of  100  tons  of  fruit  per  day. 
The  fruit  should  be  thoroughly  crushed  to  facilitate  fermentation  and 
pressing.      Orange  juice  will  ferment  more  satisfactorily  if  it  is  free 

from  the  oil  of  the  skins. 
The  oil  may  be  recov- 
ered from  oranges  on  a 
large  scale  by  methods 
described  in  Depart- 
ment Bulletin  399  of 
the  United  States  De- 
partment of  Agricul- 
ture, Washington,  D.  C. 
The  oranges  may  then 
be  crushed  after  the  oil 
cells  are  removed  by  the 
methods  given  in  that 
Fig.  2. — Filling  a  rack  and  cloth  press.  bulletin. 


VINEGAR  FROM   WASTE  FRUITS 


171 


Pressing  before  Fermentation. — If  vinegar  for  table  use  Is  to  be 
made  from  grapes,  they  should  be  pressed  as  soon  as  crushed  to  avoid 
color  and  an  astringent  taste  from  the  skins  and  stems.      Apples  are 
usually  pressed  as  soon  as  crushed,  but  a  larger  yield  of  juice  is 
obtained  and  pressing  is  more  complete  if  they  are  allowed  to  undergo 
a  partial  fermentation  before  pressing.      Oranges  and  other  fruits 
will   press   much   more   satisfactorily   if   fermented   before   pressing. 
Hand  presses  for  small-scale  operations  may  be  had  for  about  fifteen 
to  twenty-five  dollars.     Larger  presses  to  be  run  by  hydraulic  pressure 
will  cost  from  $150  to  $1000  or  more.      The  basket  and  the  rack  and 
cloth  types  of  presses  are 
best    suited     to     vinegar 
manufacture;  the  contin- 
uous press  does  not  work 
so  satisfactorily. 

ALCOHOLIC   FERMENTATION 

A.  Growth  of  Pure 
Yeast. — The  manufacture 
of  vinegar  requires  two 
fermentation  processes. 
The  first  causes  the  trans- 
formation of  the  SUffar  of  ^S-  3. — Elevator,  crusher  and  vats  for  fermentation 

°  of  crushed  fruit  before  pressing. 

<fche    fruit    or    juice    into 

alcohol.  This  is  brought  about  by  yeast.  The  second  changes  the 
alcohol  into  acetic  acid  and  is  caused  by  vinegar  bacteria. 

The  alcoholic  fermentation  must  be  complete  before  the  acetic  or 
"vinegar"  fermentation  is  allowed  to  start,  or  otherwise  the  yeast 
fermentation  will  be  stopped  by  the  acetic  acid  and  unfermented 
sugar  will  remain  in  the  vinegar.  Such  a  condition  results  in  weak 
vinegars  of  poor  quality  and  low  yields  of  acetic  acid  or  acetone. 

Alcoholic  fermentation  will  occur  naturally  by  the  growth  and 
activity  of  yeasts  present  on  the  fruits  themselves.  Such  a  fermen- 
tation is,  however,  ver}^  uncertain,  usually  very  wasteful  of  sugar, 
and  results  in  vinegars  of  varying  and  uncertain  quality. 

Selected  pure  j^east  is  necessary  to  insure  uniform,  complete  fer- 
mentations, with  maximum  yields  of  alcohol  and  minimum  waste  of 
sugar.  Pure  yeast  may  be  obtained  for  $1  per  culture  by  writing 
to  the  Division  of  Viticulture,  Hilgard  Hall,  University  of  California, 
Berkeley.     The  method  of  using  the  yeast  is  described  below: 

1.  The  yeast  as  received  from  the  University  is  in  solid  form  in 
a  bottle  plugged  with  cotton.      A  bottle  of  sterile  fruit  juice  accom- 


172 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


panies  the  yeast.  Remove  the  cotton  plug  and  fill  the  yeast  bottle 
about  three-quarters  full  with  sterile  juice  from  the  other  bottle. 
Replace  the  cotton  plug  at  once. 

2.  Leave  the  yeast  bottle  in  a  warm  place  until  the  juice  is  fer- 
menting rapidly,  as  indicated  by  the  formation  of  gas  bubbles.  Three 
or  four  days  are  usually  sufficient. 

3.  When  the  yeast  is  fermenting,  sterilize  three  to  five  gallons 
of  fresh  juice  by  heating  it  to  boiling  in  a  covered  agate  ware  or 
aluminum  pot  and  let  it  cool  overnight. 

4.  Then  add  the  contents  of  the  yeast  bottle  and  mix  the  yeast 
and  juice  by  pouring  the  juice  back  and  forth  a  few  times  with  a 

dipper  sterilized  by 
dipping  in  boiling 
water.  Everything 
that  comes  in  contact 
with  the  yeast  or  juice 
must  be  scrupulously 
clean  and  sterilized  by 
boiling  water  or  steam. 
Set  aside  in  a  warm 
place  for  three  or  four 
days.  It  will  then  be 
in  vigorous  fermenta- 
tion. This  will  be 
enough  to  start  40  gal- 
lons of  juice  as  de- 
scribed in  step  5. 

5.  Prepare  a  clean  50-gallon  barrel  for  yeast  growth  by  removing 
one  head  and  washing  the  barrel  out  with  hot  water  and  "sal  soda': 
or  soda  ash,  followed  by  rinsing  with  boiling  hot  water.  Heat  about 
40  gallons  of  juice  to  165  degrees  Fahrenheit  or  higher.  This  can 
be  done  by  placing  a  steam  hose  in  the  juice  in  the  barrel  or  by 
heating  the  juice  in  5-gallon  pots  on  a  stove.  A  dairy  thermometer 
may  be  used  to  test  the  temperature.  Allow  the  juice  to  cool  in  the 
barrel  to  90°  F.  or  lower.  Large  tin  buckets  of  cold  water  may 
be  floated  in  the  juice  to  cool  it  quickly.      They  must  be  clean. 

6.  When  the  juice  has  cooled,  add  the  three  or  four  gallons  of 
fermenting  juice  previously  prepared.  Aerate  and  mix  the  yeast 
and  juice  in  the  barrel  by  pouring  it  back  and  forth  with  a  dipper 
sterilized  in  hot  water. 

7.  Aerate  the  juice  five  or  six  times  daily  in  the  same  way  until 
it  is  fermenting  rapidly.     This  will  be  in  three  or  four  days.      It  is 


Fig.  4.— A  small  hand  press. 


VINEGAR  FROM   WASTE  FRUITS  173 

then  ready  for  use.  This  40  gallons  of  yeast  will  be  enough  for  1000 
to  2000  gallons  of  fresh  juice.  If  more  is  needed,  several  more 
barrels  of  sterile  juice  may  be  started  from  the  first  barrel. 

B.  Starting  the  First  Fermentation  Vats. — 1.  As  soon  as  the  yeast 
is  working  rapidly  in  the  yeast  barrel,  crush  the  fruit  to  be  fermented. 
To  each  ton  of  crushed  fruit  add  three-quarters  of  a  gallon  of  6  per 
cent  sulfurous-acid  solution  and  mix  it  in  bv  stirring.  This  solution 
may  be  bought  from  the  manufacturer  for  20c  to  25c  per  gallon. 
Potassium  meta-bi-sulfite  may  be  used  instead,  but  at  present  is  ver}7 
expensive.  A  solution  made  by  dissolving  one  pound  in  a  gallon 
of  water  is  used  in  the  same  way  and  the  same  amount  as  the  6  per  cent 
sulfurous-acid  solution. 


a- 


Fig.   5. — Growing   yeast   in   50-gallon    barrels.       a.   Barrels   with   sterilized   juice. 

b.  Barrels  with  yeast  growing  in  juice. 

If  apples  or  grapes  are  being  used,  press  them  and  transfer  the 
juice  to  fermentation  vats,  tanks  or  barrels.  Other  fruits  as  soon  as 
crushed  are  placed  directly  in  the  fermentation  vessels.  The  pressed 
apple  pomace  is  placed  in  a  separate  vat;  it  contains  juice  that  may 
be  recovered  by  pressing  after  fermentation. 

2.  A  few  hours  after  sulfiting,  add  five  to  ten  gallons  of  the  yeast 
to  each  ton  of  crushed  fruit  or  each  200  gallons  of  juice  and  mix 
thoroughly. 

3.  If  crushed  fruit  is  being  fermented,  stir  it  once  daily  during 
fermentation  to  prevent  molding  and  vinegar  fermentation  in  the 
top  of  the  fermenting  mass. 

C.  Starting  Other  Vats. — When  this  first  vat  is  in  fermentation  it 
may  be  used  to  start  other  vats.     To  the  second  vat  add  a  half -gallon 


174  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 

of  6  per  cent  sulfurous-acid  solution  per  ton  of  crushed  fruit  or  per 
200  gallons  of  juice.  Then  add  20  gallons  of  the  rapidly  fermenting 
juice  or  crushed  fruit  from  the  first  vat  per  ton  of  crushed  fruit  and 
mix.  When  this  vat  is  fermenting  other  vats  may  be  started  from 
it  in  the  same  way  that  the  second  was  started  from  the  first  and  the 
same  system  may  be  applied  to  all  succeeding  vats.  If  the  yeast  at 
any  time  seems  to  work  poorly,  a  new  start  should  be  obtained  from 
the  University. 

Pressed  apple  pulp  or  pomace  is  fermented  by  adding  fermenting 
juice  to  it  in  a  vat.  Use  about  10  gallons  to  each  100  gallons  of 
pomace.  It  is  pressed  again  after  fermentation.  A  great  deal  of 
juice  can  be  obtained  in  this  way. 

D.  Pressing  Fermented 
Fruits. — If  the  fruits  have  not 
been  pressed  before  fermenta- 
tion they  should  be  pressed 
after  about  four  days'  fermen- 
tation. Fermentation  before 
pressing  softens  the  fruit  and 
greatly  increases  the  yield  of 
juice.  Usually  a  great  deal  of 
the    fermented    juice    may    be 

-c,.     a     -rT  .      n        ,    ■,  -  ',  •     n  .  ..      drawn    off    before    pressing    so 

Fig.  6. — Vats  of  crushed  fruit  in  fermentation.  ^  to 

that  only  the  residual  pulp  need 
be  pressed.  Press  thoroughly  and  transfer  the  juice  to  tanks  or 
barrels  to  finish  fermenting. 

E.  Completion  of  Fermentation. — The  juice  is  allowed  to  ferment 
until  practically  all  of  the  sugar  is  converted  into  alcohol  and  carbonic 
acid  gas.  If  conditions  are  favorable  this  will  be  in  about  three  weeks 
or  less.  It  is  complete  when  there  is  no  taste  of  sugar  present  and 
when  gas  is  no  longer  given  off.  The  progress  of  the  fermentation 
can  be  watched  by  means  of  a  Balling  sugar  tester  or  hydrometer. 
This  instrument  indicates  approximately  the  amount  of  sugar  present. 
The  Balling  hydrometer  may  be  obtained  from  any  chemical  supply 
house  directly  or  through  a  drug  store  for  about  75c.  A  tall  glass 
or  tin  cylinder  will  also  be  needed.  To  make  the  test  pour  the  juice 
into  the  cylinder,  insert  the  hydrometer  and  read  the  per  cent  of  sugar 
indicated  at  the  surface  of  the  liquid. 

The  vats  and  all  apparatus  coming  in  contact  with  the  juice  should 
be  clean.  Each  vat  should  be  started  with  yeast  from  the  preceding 
vat  or  from  a  pure-yeast  apparatus  as  described  above.  If  these 
precautions  are  observed  good  fermentations  will  result. 


VINEGAR  FROM   WASTE  FRUITS  175 

F.  Storage  after  Fermentation. — The  fermented  juice  should  be 
allowed  to  settle  for  two  to  three  weeks  after  alcoholic  fermentation 
is  over.  This  is  to  rid  it  of  yeast  and  pulp,  etc.  During  this  settling- 
process  the  tanks  or  barrels  should  be  kept  full  to  prevent  growth  of 

'wine  flowers'1   on  the  exposed  surface.      Closed  tanks  should  be 
employed. 

G.  Racking. — When  the  yeast  and  sediment  has  settled,  the  fer- 
mented juice  must  be  ' '  racked ' ' ;  that  is,  drawn  off  from  the  sediment 
into  other  tanks  or  barrels.  This  can  be  done  by  means  of  a  faucet 
near  the  bottom  or  by  syphoning  with  a  hose  from  the  top  and  by 
pumping,  or  running  by  gravity  into  the  new  tanks,  according  to 
conditions  and  equipment.  The  sediment  may  be  discarded,  filtered 
or  allowed  to  settle  in  barrels.  By  the  last  method  more  fermented 
juice  may  be  recovered  from  the  otherwise  waste  sediment. 

If  left  in  the  juice,  the  sediment  may  give  a  bad  flavor  and  inter- 
fere with  acetic  fermentation  and  the  clearing  of  the  vinegar. 

DISTILLATION     BEFORE    ACETIC-ACID    FERMENTATION 

Where  the  fermented  juice  contains  a  great  deal  of  suspended 
matter  and  where  it  is  desired  to  make  a  vinegar  of  very  high  acid 
strength  to  be  used  in  the  manufacture  of  acetic  acid  or  acetone,  the 
fermented  juice  should  be  distilled.  This  will  separate  the  alcohol 
from  the  impurities  of  the  juice  and  a  fairly  high  acetic  acid  can  be 
made  by  passing  this  distilled  liquid  through  generators.  It  is  cus- 
tomary to  carry  out  this  distillation  in  large  continuous  stills  which 
give  a  distillate  of  about  10  per  cent  alcohol.  Distillation,  however, 
is  only  used  in  large  establishments  and  the  equipment  necessary  is 
too  expensive  for  the  small-scale  manufacturer.  With  the  distillation 
process  it  is  possible  to  recover  all  of  the  alcohol  from  the  pressed 
fermented  pomace  by  washing  or  leaching  with  water  and  then  dis- 
tilling the  alcoholic  wash.  If  fruits  are  to  be  used  on  a  very  large 
scale  for  the  manufacture  of  acetic  acid  and  acetone,  it  is  recom- 
mended that  the  distillation  process  be  installed  because  all  of  the 
alcohol  is  then  recovered  and  a  purer  acid  obtained. 

ACETIC-ACID   FERMENTATION 

A.  Acidification. — The  transformation  of  the  alcohol  in  the  fer- 
mented juice  is  carried  on  by  vinegar  bacteria.  They  will  not  work 
efficiently  and  will  not  start  quickly  unless  the  fermented  juice  after 
alcohol  fermentation  is  acidified  and  inoculated  with  vinegar  bacteria. 
These  two  objects  are  accomplished  by  the  addition  of  new  vinegar 
to  the  fermented  juice  after  it  has  been  racked,  or  to  the  alcoholic 
distillate  from  the  still.      The  fermented  liquid  should  be  acidified 


176 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


with  at  least  one  gallon  of  strong  new  vinegar  to  each  three  gallons 
of  the  fermented  juice.  This  new  vinegar  will  carry  with  it  large 
quantities  of  vinegar  bacteria  which  will  heavily  inoculate  the  fer- 
mented juice  and  cause  a  rapid  start  of  vinegar  fermentation.  After 
acidifying  in  this  way,  the  vinegar  fermentation  is  carried  out  by 
either  one  of  the  processes  described  below : 

B.  Slow  Process. — The  slow  process  is  carried  out  in  barrels  or 
other  containers  and  requires  several  months  to  a  year  for  completion. 
It  is  greatly  hastened  by  the  addition  of  vinegar  as  noted  under  ' '  A. ' : 
If  it  is  carried  out  in  barrels,  they  should  be  filled  about  three-quarters 
full.  The  bung  of  the  barrel  should  be  removed  and  the  bunghole 
covered  with  a  wire  screen  or  a  cheesecloth  to  keep  out  insects.  At 
each  end  of  the  barrel,  slightly  above  the  level  of  the  liquid,  two  holes 


^^ 


1 

I 


a 


^\^\W\^ 


Fig.  7. — Barrel  arranged  for  slow  process  of  vinegar  fermentation,  a.  Three- 
quarter  inch  holes  at  each  end  of  barrel,  covered  with  screen  or  cheesecloth,  b. 
Bunghole.      c.  Wooden  spigot,      d.  Level  of  vinegar. 

should  be  bored  each  about  one  inch  in  diameter.  These  holes  should 
also  be  screened  to  keep  out  vinegar  flies,  etc.  The  barrels  should 
be  kept  in  a  warm  place  and  should  not  be  disturbed  during  the 
vinegar  process.  The  vinegar  is  simply  allowed  to  remain  in  the 
barrels  until  it  has  reached  its  maximum  strength.  About  three- 
quarters  of  the  vinegar  can  then  be  drawn  off  into  other  barrels  and 
newly  fermented  and  settled  juice  can  be  added  to  the  remaining 
one-fourth  of  the  vinegar.  This  new  lot  of  fermented  juice  and 
vinegar  is  then  allowed  to  acetify.  This  process  can  be  repeated 
indefinitely,  starting  the  new  lot  of  fermented  juice  each  time  with 
one-fourth  of  the  new  vinegar  left  in  the  barrels.  This  method  is 
known  as  the  "Orleans"  process  and  is  the  best  of  all  slow  processes. 
It  is  a  mistake  to  simply  allow  the  vinegar  fermentation  to  depend 
on  chance  because  great  risk  is  run  of  having  the  vinegar  completely 


VINEGAR  FROM   WASTE  FRUITS  177 

spoiled  or  of  getting  an  inferior  product.      This  is  especially  true  of 
orange  vinegar. 

C.  Testing  the  Vinegar. — The  vinegar  fermentation,  whatever 
process  employed,  should  be  watched  carefully  by  testing  the  acid 
strength  from  time  to  time.  If  this  is  to  be  done  very  accurately, 
a  standard  sodium-hydroxide  solution  and  the  necessary  instruments 
should  be  obtained  from  a  reliable  chemical  supply  house  which  will 
furnish  the  equipment  with  instructions  for  use.  The  Leo  Acid 
Tester  is  simpler  and  sufficiently  accurate  for  factory  use.  This  small 
instrument  can  be  obtained  from  any  of  the  chemical  supply  houses 
directly  or  through  a  local  druggist.  The  cost  is  about  five  dollars 
or  less.  It  gives  the  strength  of  the  vinegar  in  ' '  grains. ' '  The  Pure 
Food  Law  requires  that  a  vinegar  shall  have  at  least  4  per  cent  acid 
or  be  "40-grain  vinegar."  It  can  be  above  this  and  usually  is  if 
it  is  a  pure  vinegar.  A  good  tester  is  necessary  in  the  manufacture 
of  any  considerable  quantity  of  vinegar.  Directions  accompany  the 
Leo  Tester.     Bulletin  227  of  this  station  also  tells  how  to  use  it. 

The  vinegar  fermentation  should  continue  until  there  is  no  further 
increase  in  acid.  This  indicates  that  it  is  complete.  A  good  cider 
vinegar  should  reach  a  strength  of  "60  grains."  A  wine  vinegar 
should  reach  "75  to  100  grains.'  A  good  orange  vinegar  should 
reach  at  least  "45  to  50  grains.'  A  "distilled"  vinegar  made  from 
an  alcoholic  distillate  containing  10  per  cent  alcohol  will  reach  "90 
to  95  grains. '  A  distilled  vinegar  can  be  made  only  by  the  generator 
process.* 

D.  Generator  Process. — The  rate  of  vinegar  fermentation  depends 
upon  the  amount  of  air  supplied  to  the  vinegar  bacteria.  Vinegar 
generators  merely  increase  the  amount  of  surface  of  vinegar  exposed 
to  the  air.  The  surface  is  a  great  many  times  that  which  would  be 
exposed  in  an  ordinary  barrel.  Therefore,  the  rate  of  acidification 
is  enormously  increased.  Most  generators  consist  of  an  upright  tower 
filled  with  beechwood  shavings  or  other  suitable  material,  such  as 
rattan  shavings  or  coarse  coke  or  charcoal.  For  fruit  juices,  beech- 
wood  shavings  will  be  found  best.  Figure  8  shows  a  plan  of  a 
generator. 

To  use  the  generator,  it  is  first  filled  with  clean  beechwood  shavings. 
The  shavings  are  then  wet  by  running  strong  new  vinegar  through 
them  until  they  are  saturated.  The  generator  is  equipped  with  a 
tilting  trough  C  which  distributes  the  vinegar  over  the  head,  from 
which  it  flows  down  over  the  shavings  through  numerous  holes.      This 


*  See  also  ' '  Cider  Vinegar  by  the  Quick  Process, ' '  published  by  the  Hydraulic 
Press  Mfg.  Co.,  Mt.  Gilead,  Ohio.     Sent  free  on  application  to  above  address. 


178 


UNIVERSITY  OF  CALIFORNIA- — EXPERIMENT  STATION 


vinegar  should  be  run  through  the  generator  several  times  until  the 
shavings  are  saturated.  The  alcoholic  liquid  which  has  been  acidified 
with  one-fourth  its  volume  of  new  vinegar  is  then  started  slowly 
through  the  generator.  The  usual  rate  of  flow  is  not  more  than  25 
gallons  per  day  of  24  hours.  At  first,  the  liquid  issuing  from  the 
generator  will  not  be  strong  vinegar,  but  after  three  or  four  days 
of  running,  the  vinegar  bacteria  will  multiply  in  the  shavings  suf- 


sa«as>*«S!?**»i?ss*s!a«:  ^is*ssas»i««sa«sa«i\* 


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Fig.  8. — Upright  generator.  A.  Supply  pipe.  B.  Cover.  C.  Tilting  trough. 
D.  False  head.  E.  Main  chamber  filled  with  shavings.  F.  Thermometer.  G. 
False  bottom  to  support  shavings.    H.  Air  inlets.     I.  Outlet. 


ficiently  to  cause  a  rapid  fermentation  so  that  finally  the  vinegar  as 
it  comes  through  at  the  rate  of  25  gallons  per  day  or  less  will  come 
out  vinegar  of  the  maximum  strength  possible  with  the  raw  material 
being  used.  The  rate  of  flow  and  the  air  supply  which  comes  through 
the  small  inlets  at  the  bottom  of  the  generator  are  so  regulated  that 
a  temperature  of  about  80  to  85  degrees  F.  is  maintained.  A  ther- 
mometer, inserted  as  shown  in  the  drawing,  near  the  center  of  the 
generator,  will  indicate  the  temperature. 

With  clear  juice  and  careful  manipulation,  the  generator  can  be 
kept  running  for  six  or  seven  months  without  cleaning.  It  will  in 
time,  however,  become  clogged  with  sediment  so  that  it  will  not  act 


VINEGAR  FROM   WASTE  FRUITS 


179 


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Fig.  9. — Revolving  generator  for  factory  use.  a.  Air  inlet.  b.  Air  inlet 
with  regulating  wooden  plug.  c.  Thermometer,  d.  Wall  of  outer  chamber  which 
encloses  cylinder  e.  e.  Revolving  cylinder  filled  with  beechwood  shavings.  /. 
Air  inlets  to  e.  g.  Shaft  and  pulley  to  rotate  e;  e  rotates  about  once  per  hour. 
h.  Liquid,  usually  about  500   gallons,     i.   Beechwood  shavings.     .;'.   Supports   for 


generator. 


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Fig.  10. — Rotating  generator  made  from  barrel  filled  with  beeclnvood  shavings. 
a.  Air  inlets  at  ends  of  barrel.  ~b.  Wooden  partitions  in  barrel  perforated  to  allow 
passage  of  air.  c.  Shavings,  d.  Vinegar,  e.  Upper  spigot,  open.  /.  Lower  spigot, 
closed.  As  barrel  rotates  /  becomes  upper  and  e  lower  spigot.  #.3X6  inch 
skids  for  barrel. 


180  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

efficiently.  It  must  then  be  stopped  and  the  shavings  washed  in  hot 
water.  They  can  then  be  dried  in  the  sun  and  returned  to  the  gen- 
erator. The  filled  generator  should  never  be  stopped  for  more  than 
twenty-four  hours  at  a  time  because  the  shavings  will  become  diseased 
and  moldy  if  the  generator  is  not  kept  in  operation. 

A  type  of  generator  that  need  not  be  cleaned  so  often  is  the  hori- 
zontal revolving  type.  This  generator  consists  of  a  cylinder  filled 
with  shavings.  It  is  enclosed  in  a  wooden  air-tight  box  with  air  inlets. 
The  lower  half  of  the  cylinder  is  immersed  in  acidified  fermented 
juice,  the  upper  half  is  exposed  to  the  air.  The  cylinder  rotates 
slowly.  Acetification  takes  place  in  the  exposed  upper  half.  The 
Temperature  is  maintained  at  80-85  degrees  F.  by  regulating  the  air 
inlets  and  rate  of  turning.  The  generator  usually  holds  about  500 
gallons  (see  fig.  9).  A  simple  form  of  rotating  generator  is  a  barrel 
filled  with  shavings.  Air  vents  are  made  in  the  centers  of  the  heads 
of  the  barrel.  It  is  filled  half  full  of  acidified  fermented  juice.  It 
is  turned  half  way  over  several  times  daily  to  expose  new  shavings 
to  the  air  (see  fig.  10). 

Distilled  vinegar,  which  is  made  from  an  alcoholic  distillate  of 
fermented  fruit  juice  or  other  material,  is  made  in  generators  filled 
with  beechwood  shavings,  or,  better,  with  pieces  of  charcoal  or  coke. 
Charcoal  and  coke  cannot  be  used  for  undistilled  fruit  juices  because 
they  soon  become  inactive  through  the  accumulation  of  sediment. 

Aging. — When  the  vinegar  has  reached  its  maximum  strength, 
either  by  the  slow  or  the  generator  process,  it  must  be  aged  before  it 
is  at  its  best  quality  for  table  use.  The  aging  process  takes  place 
during  storage  and  results  in  an  improvement  in  flavor  and  in  clear- 
ness. The  best  vinegar  is  aged  at  least  a  year  before  it  is  put  on 
the  market.  The  aging  should  take  place  in  tanks  or  in  barrels 
which  are  kept  full  and  closed. 


CLARIFICATION    AND    FILTRATION 

Well  made  vinegar  from  good  material  will  very  often  clear  suf- 
ficiently during  the  aging  process  to  make  it  suitable  for  bottling. 
Usually;  however,  it  will  be  necessary  to  aid  the  clearing  by  filtration 
or  by  the  addition  of  some  clarifying  substance. 

A.  Clarification. — Two  substances  are  in  common  use  for  the 
clarification  of  vinegar,  viz.,  fish  isinglass  and  Spanish  clay.  Isinglass 
is  the  more  expensive,  but  produces  the  most  perfect  clearness.  The 
usual  amount  of  isinglass  necessary  to  clarify  cider  vinegar  is  about 
one  ounce  per  hundred  gallons,  although  this  will  vary  considerably 


VINEGAR  FROM   WASTE  FRUITS  181 

with  the  condition  of  the  vinegar.  The  isinglass  is  weighed  out  and 
broken  up  into  small  pieces.  It  is  then  mixed  with  one  gallon  of 
vinegar  for  each  ounce  of  isinglass.  It  is  allowed  to  soak  until  the 
isinglass  becomes  swollen  and  soft.  Warming  the  mixture  will  aid 
in  dissolving  the  isinglass.  The  isinglass  is  then  broken  up  very 
thoroughly  and  mixed  with  the  vinegar  until  a  solution  free  from 
lumps  is  obtained.  The  mixture  should  be  passed  through  a  fine 
sieve  and  the  lumps  retained  well  broken  up.  This  solution  of 
isinglass  is  then  added  to  the  vinegar  at  the  rate  of  one  gallon  for 
each  hundred  gallons  of  vinegar  to  be  clarified.  It  must  be  empha- 
sized that  the  isinglass  must  be  made  into  a  very  smooth  solution 


Fig.   11. — A  small  barrel   arranged  to   mix   clay,   or   other   clarifying  agent,   and 

water  by  agitation. 


before  it  is  used.  Otherwise,  the  clarification  will  be  imperfect. 
The  vinegar  and  isinglass  are  then  mixed  thoroughly  in  a  barrel  or 
tank  by  stirring.  The  mixture  is  allowed  to  stand  until  the  isinglass 
settles,  leaving  a  clear  liquid  above.  The  clear  vinegar  can  then  be 
drawn  off  with  a  hose  or  from  a  faucet.  The  sediment  can  be 
drained  off  and  filtered. 

Spanish  clay  is  used  in  a  similar  way.  It  is  mixed  with  water 
at  the  rate  of  one  pound  to  each  gallon  of  water,  and  allowed  to  soak 
for  several  days  until  it  becomes  soft.  It  is  then  worked  up  with  the 
hands  or  by  continuous  agitation  to  give  a  thin,  smooth  mud  or  sus- 
pension of  clay.  The  clay  must  be  broken  up  very  finely.  The  device 
shown  in  fig.  11  shows  a  convenient  method  of  mixing  the  clay  and 
water  in  a  rotating  ten-gallon  barrel. 


182  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

They  are  placed  in  this  barrel  which  is  set  rotating  slowly.  Within 
a  few  hours  the  mixing  is  complete.  For  each  100  gallons  of  vinegar 
to  be  clarified,  the  amount  of  clay  will  be  from  three  to  six  pounds; 
that  is,  from  three  to  six  gallons  of  the  one  pound  per  gallon  clay 
solution.  This  solution  is  mixed  with  the  vinegar  by  stirring  and 
is  allowed  to  settle  in  the  same  way  as  directed  for  isinglass. 

The  amount  of  clay  to  be  used  will  vary  with  the  cloudiness  and 
condition  of  the  vinegar.  Where  an  attempted  isinglass  clarification 
has  failed  the  vinegar  can  be  treated  successfully  with  Spanish  clay 
later,  or  often  isinglass  and  clay  may  be  added  together  with  good 
results. 

B.  Filtration. — Where  large  amounts  of  vinegar  are  to  be  made, 
clarifying  often  becomes  impracticable  and  filtration  is  resorted  to 
because  of  its  cheapness  and  because  very  large  volumes  can  be 
handled  rapidly.  Any  of  the  standard  types  of  filters,  such  as  the 
Karl  Kieffer,  the  International,  or  the  Seitz  Filter,  can  be  used  suc- 
cessfully for  vinegar,  if  the  interior  of  the  filter  is  heavily  coated 
with  tin  to  protect  it  from  the  action  of  the  acid.  For  small-scale 
operations,  a  cloth  bag  filter,  costing  five  to  ten  dollars,  can  be  used. 
The  efficiency  of  the  bag  filter  is  increased  if  a  small  amount  of 
infusorial  earth  (Kieselguhr)  is  added  to  the  vinegar  before  filtration. 

Bottling. — For  bottling  purposes  vinegar  should  be  aged  and  per- 
fectly bright.  If  the  operations  previously  described  have  been  car- 
ried out  successfully,  the  vinegar  will  be  in  this  condition.  Bottles 
should  be  filled  full  and  well  corked  so  that  bacteria  will  not  grow 
in  the  vinegar  and  cause  it  to  become  cloudy.  Vinegar  clarified  with 
isinglass  will  remain  bright  in  the  bottles  more  satisfactorily  than 
vinegar  clarified  with  Spanish  clay.  Ordinary  grape  juice  bottles 
or  other  type  of  Crown  finish  bottles  make  very  satisfactory  containers 
for  vinegar,  because  the  capping  is  less  expensive  and  troublesome 
than  corking  and  the  appearance  is  attractive. 


VINEGAR   DISEASES 

Lactic  Bacteria. — Fermented  fruit  juices  that  have  not  been  fer- 
mented with  pure  yeast  usually  develop  lactic-acid  bacteria.  These 
bacteria  are  also  known  as  "tourne  bacteria"  and  are  very  common. 
They  produce  a  disagreeable  taste,  cloudiness  and  lactic  acid  in  the 
fermented  juice.  These  persist  in  the  vinegar  and  reduce  its  quality. 
The  lactic-acid  bacteria  can  be  avoided  if  pure  yeast  and  a  small 
amount  of  sulfurous  acid  are  used  in  the  way  described. 


VINEGAR  FROM   WASTE  FRUITS  183 

Wine  Flowers. — If  the  fermented  fruit  juice  is  left  in  open  tanks, 
it  will  become  coated  with  "wine  flowers,"  a  form  of  wild  yeast  that 
destroys  alcohol  and  flavor  and  causes  cloudiness.  It  can  be  avoided 
by  storing  the  fermented  juice  in  filled  and  closed  barrels  or  tanks 
and  its  development  can  be  checked  in  open  tanks  by  the  addition  of 
one  gallon  of  new  vinegar  to  each  three  gallons  of  fermented  juice, 
as 'directed  under  vinegar  fermentation. 

Vinegar  Eels. — Vinegar  often  becomes  infested  with  small  nema- 
tode worms  known  as  "vinegar  eels."  These  little  eels  are  about  an 
eighth  of  an  inch  long  and  can  be  seen  by  holding  the  vinegar  in  a 
glass  to  the  light.  They  destroy  the  acid  and  are  very  unpleasant 
in  appearance.  If  the  fermented  juice  or  vinegar  in  the  factory 
becomes  badly  infested,  all  the  juice  and  all  of  the  tanks  must  be 
sterilized  by  heat  to  rid  the  factory  of  them.  Vinegar  infested  with 
eels  can  be  sterilized  by  heating  to  about  130  degrees  F.,  at  which 
temperature  the  eels  are  killed.  Tanks  and  barrels  that  have  been 
infested  should  be  sterilized  by  steam.  The  same  applies  to  generators 
which  often  become  contaminated  with  this  pest.  A  sterilizer  can 
be  made  by  surrounding  a  piece  of  tin  pipe,  10  feet  or  more  in  length, 
with  a  steam  jacket  made  of  iron  pipe.  The  vinegar  or  cider,  etc., 
is  passed  through  the  tin  pipe,  which  is  heated  by  steam.  The  hot 
vinegar  or  fermented  juice  can  be  cooled  by  passing  it  through  a 
coil  of  tin  pipe  immersed  in  water. 


SUMMARY 

1.  Vinegar  making  depends  on  two  fermentations.  The  first  is 
fermentation  of  the  sugar  to  alcohol  and  carbonic  acid  gas  by  yeast. 
The  second  is  the  transformation  of  the  alcohol  into  acetic  acid  by 
vinegar  bacteria.  The  fermentations  must  be  kept  separate  and 
distinct  to  get  good  results. 

2.  Pure  yeast  and  a  small  amount  of  sulfurous  acid  should  be  used 
to  insure  good  alcoholic  fermentation  and  to  eliminate  lactic  bacteria. 

3.  Most  fruits  can  be  pressed  most  satisfactorily  if  crushed  and 
fermented  before  pressing. 

4.  The  fermented  juice  should  be  stored  several  weeks  to  rid  it 
of  yeast  and  other  solid  particles  and  should  then  be  "racked''  or 
drawn  off  the  sediment  before  vinegar  fermentation  commences. 

5.  To  the  racked  juice,  should  be  added  one-fourth  its  volume 
of  new  vinegar  to  start  acetic  fermentation  and  prevent  vinegar 
diseases. 


184  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

6.  The  acidified  fermented  juice  may  then  be  made  into  vinegar 
by  the  slow  process  in  barrels  or  by  the  quick  process  in  generators. 
Vinegar  fermentation  requires  an  abundance  of  air. 

7.  The  progress  of  the  acetification  should  be  watched  by  the  Leo 
tester  or  other  means. 

8.  The  vinegar  should  be  aged  for  a  year  before  sale  if  a  high 
quality  is  desired. 

9.  Vinegar  may  be  clarified  by  isinglass  or  Spanish  clay,  or  by 
filtration. 

10.  Lactic-acid  bacteria  injure  the  quality  of  vinegar,  but  are 
avoided  if  pure  yeast  is  used;  wine  flowers  destroy  alcohol,  but  are 
prevented  if  the  fermented  juice  is  acidified  with  one-fourth  its  volume 
of  new  vinegar;  vinegar  eels  are  destroyed  by  heating  the  fermented 
juice  or  vinegar  to  130  degrees  F. 

Publications. — Write  to  the  State  Pure  Food  and  Drug  Labora- 
tory, University  of  California,  Berkeley,  for  a  copy  of  the  State  Food 
and  Drug  Regulations. 

Bulletin  213  and  Circulars  119  and  140  of  the  Experiment  Station, 
obtainable  free  of  charge  on  written  application  to  the  Dean's  Office, 
College  of  Agriculture,  Berkeley,  will  be  found  of  great  assistance 
in  the  use  of  pure  yeast  and  control  of  alcoholic  fermentation. 

A  chapter  in  Marshall's  Microbiology  on  vinegar  manufacture,  by 
Prof.  F.  T.  Bioletti,  may  also  be  consulted. 


STATION   PUBLICATIONS    AVAILABLE   FOR   FREE   DISTRIBUTION 


REPORTS 

1897.      Resistant  Vines,   their  Selection,   Adaptation,   and  Grafting.      Appendix  to  Viticultural 
Report  for  1896. 

1902.  Report  of  the  Agricultural  Experiment   Station  for   1898-1901. 

1903.  Report  of  the  Agricultural  Experiment   Station  for   1901-03. 

1904.  Twenty-second  Report  of  the  Agricultural  Experiment  Station  for    1903-04. 

1914.  Report  of  the  College  of  Agriculture  and  the  Agricultural   Experiment  Station,    July, 

1913-June,    1914. 

1915.  Report  of  the  College  of  Agriculture  and  the  Agricultural   Experiment   Station,    July, 

1914-June,    1915. 

1916.  Report  of  the  College  of  Agriculture   and  the  Agricultural   Experiment   Station,    July, 

1915-June,    1916. 

1917.  Report   of  the   College  of  Agriculture  and  the   Agricultural   Experiment   Station,    July, 

1916-June,   1917. 

BULLETINS 


No. 

230. 
241. 
242. 

244. 
246. 
248. 

249. 
250. 
251. 


252. 
253. 

255. 
257. 
261. 

262. 

263. 
264. 
265. 
266. 

267. 


Enological  Investigations. 

Vine  Pruning  in  California,  Part  I. 

Humus  in  California  Soils. 

Utilization  of  Waste  Oranges. 

Vine  Pruning  in  California,   Part  II. 

The  Economic  Value  of   Pacific  Coast 

Kelps. 
Stock-Poisoning  Plants  of  California. 
The  Loquat. 
Utilization  of  the  Nitrogen  and  Organic 

Matter   in    Septic    and    Imhoff    Tank 

Sludges. 
Deterioration  of  Lumber. 
Irrigation   and   Soil   Conditions   in   the 

Sierra  Nevada  Foothills,  California. 
The   Citricola    Scale. 
New  Dosage  Tables. 
Melaxuma    of    the    Walnut,     "Juglans 

regia." 
Citrus   Diseases   of   Florida   and   Cuba 

Compared  with  Those  of  California. 
Size  Grade  for  Ripe  Olives. 
The  Calibration  of  the  Leakage  Meter. 
Cottony  Rot  of  Lemons  in  California. 
A  Spotting  of  Citrus  Fruits  Due  to  the 
Action  of  Oil  Liberated  from  the  Rind. 
Experiments  with  Stocks  for  Citrus. 


No. 

268. 

270. 


271. 
272. 
273! 

274. 

275. 

276. 
277. 
278. 
279. 
280. 

281. 

282. 

283. 
284. 
285. 
286. 
287. 


Growing  and  Grafting  Olive  Seedlings. 

A  Comparison  of  Annual  Cropping,  Bi- 
ennial Cropping,  and  Green  Manures 
on  the  Yield  of  Wheat. 

Feeding  Dairy  Calves  in  California. 

Commercial  Fertilizers. 

Preliminary  Report  on  Kearney  Vine- 
yard Experimental  Drain. 

The  Common  Honey  Bee  as  an  Agent 
in   Prune   Pollination. 

The  Cultivation  of  Belladonna  in  Cali- 
fornia. 

The  Pomegranate. 

Sudan  Grass. 

Grain   Sorghums. 

Irrigation  of  Rice  in  California. 

Irrigation  of  Alfalfa  in  the  Sacramento 
Valley. 

Control  of  the  Pocket  Gophers  in  Cali- 
fornia. 

Trials  with  California  Silage  Crops  for 
Dairy  Cows. 

The  Olive  Insects  of  California. 

Irrigation  of  Alfalfa  in  Imperial  Valley. 

The  Milch  Goat  in  California. 

Commercial  Fertilizers. 

Vinegar  from  Waste  Fruits. 


No. 
113. 
114. 
115. 
121. 

124. 
126. 
127. 
128. 
129. 
131. 
133. 
134. 
135. 
136. 
137. 
138. 
139. 


140. 

141. 

142. 

143. 

144. 
145. 

147. 
148. 
150. 
151. 


Correspondence  Courses  in  Agriculture. 

Increasing  the  Duty  of  Water. 

Grafting  Vinifera  Vineyards. 

Some  Things  the  Prospective  Settler 
Should  Know. 

Alfalfa   Silage  for  Fattening  Steers. 

Spraying  for  the  Grape  Leaf  Hopper. 

House  Fumigation. 

Insecticide  Formulas. 

The  Control  of  Citrus  Insects. 

Spraying  for  Control  of  Walnut  Aphis. 

County  Farm  Adviser. 

Control  of  Raisin   Insects. 

Official  Tests  of  Dairy  Cows. 

Melilotus  Indica. 

Wood  Decay  in  Orchard  Trees. 

The  Silo  in  California  Agriculture. 

The  Generation  of  Hydrocyanic  Acid 
Gas  in  Fumigation  by  Portable  Ma- 
chines. 

The  Practical  Application  of  Improved 
Methods  of  Fermentation  in  Califor- 
nia Wineries  during  1913  and  1914. 

Standard  Insecticides  and  Fungicides 
versus  Secret  Preparations. 

Practical  and  Inexpensive  Poultry  Ap- 
pliances. 

Control  of  Grasshoppers  in  Imperial 
Valley. 

Oidium  or  Powderv  Mildew  of  the  Vine. 

Suggestions  to  Poultrymen  concerning 
Chicken   Pox. 

Tomato   Growing  in   California. 

"Lunjrworms." 

Round  Worms  in   Poultry. 

Feeding  and  Management  of  Hogs. 


CIRCULARS 

No. 
152. 


153 

154, 

155. 
156. 
157. 
158. 
160. 
161. 
162. 

164. 
165. 

166. 
167. 
168. 

169. 
170. 

171. 
172. 
173. 

174. 
175. 

176. 

177. 

178. 


Some  Observations  on  the  Bulk  Hand- 
ling of  Grain  in  California. 

Announcement  of  the  California   State 
Dairy  Cow  Competition,    1916-18. 

Irrigation   Practice  in  Growing   Small 
Fruits  in  California. 

Bovine  Tuberculosis. 

How  to  Operate  an  Incubator. 

Control  of  the  Pear  Scab. 

Home  and  Farm  Canning. 

Lettuce    Growing   in    California. 

Potatoes  in  California. 

White    Diarrhoea    and    Coccidiosis    of 
Chicks. 

Small  Fruit  Culture  in  California. 

Fundamentals    of    Sugar    Beet    under 
California  Conditions. 

The  County  Farm  Bureau. 

Feeding  Stuffs  of  Minor  Importance. 

Spraying  for  the  Control  of  Wild  Morn- 
ing-Glory within  the  Fog  Belt. 

1918  Grain  Crop. 

Fertilizing  California  Soils  for  the  1918 
Crop. 

The  Fertilization  of  Citrus. 

Wheat  Culture. 

The    Construction    of    the    Wood-Hoop 
Silo. 

Farm   Drainage   Methods. 

Progress  Report  on  the  Marketing  and 

Distribution    of    Milk. 
Hog      Cholera      Prevention      and      the 
Serum    Treatment. 

Grain    Sorghum    Seed. 

The    Packing   of   Apples   in   California. 


